When a new user finishes profile setup, OnboardingViewModel.finishProfile
saves the discovered+tested relays locally and publishes a kind 10002
relay list event. Insert wss://relay.wisp.talk into that list before
saving and publishing, so every new Wisp account advertises Wisp's relay
to the network from day one.
Read+write so the new user both publishes to and reads from it. Dedup
on URL (case-insensitive) so we don't duplicate if probing already
discovered the relay independently.
Reverts the earlier change to RelayConfig.DEFAULTS — that was the wrong
place. The DEFAULTS list is a fallback for users without an onboarding
flow; new-account injection belongs in onboarding where the relay list
event is actually constructed and published.